A photonic crystal (PC) has a periodic array of features (e.g., holes) in a background medium. Various devices can be fabricated by modifying the basic structure of a photonic crystal. For example, a PC cavity can be formed by a small cluster of missing holes in a PC lattice (effectively forming a point defect in the PC). As another example, a PC waveguide can be formed by a line of missing holes in a PC lattice.
Photonic crystal devices can readily be fabricated on various semiconducting and/or dielectric substrates. However, it is often difficult to efficiently couple to the resulting PC devices. For example, PC devices fabricated in semiconducting materials typically have small optical mode sizes that can be difficult to efficiently couple to convenient structures, such as optical fibers.
Accordingly, it would be an advance in the art to provide improved fiber coupling of PC devices.